Rivers were the arteries of our first civilizations - the Tigris and Euphrates of Mesopotamia, India's Ganges, Egypt's Nile, the Yellow River of China - and have nourished modern cities from London to New York, so it is natural that poets have for centuries drawn essential meanings and metaphors from their endless currents. English poets from Shakespeare and Dryden, Wordsworth and Byron to Ted Hughes, John Betjeman and Alice Oswald; Irish poets - Eavan Boland, Seamus Heaney, Paul Muldoon, to name but a few; Scottish and Welsh poets from Henry Vaughan and Robert Louis Stevenson to Robin Robertson and Gillian Clarke. A whole raft of American poets from Whitman, Emerson and Emily Dickinson to Langston Hughes, Mary Oliver, Natasha Trethewey and Grace Paley. Folk songs. African-American.